In the above co-pending patent application there is disclosed a method and an apparatus for removing deteriorated structural concrete from a road bed, for illustration, where the action of the water jetting against the concrete in a systematically controlled manner under pressures up to 25,000 p.s.i. results in areas of the structural concrete being removed to required depths to expose the steel reinforcing bars. The high pressure rotating water jets travel back and forth over the work area removing the structural concrete under controlled conditions. The weakened concrete is removed without damaging the reinforcing bars and at the same time scale and corrosion are removed from the steel bars.
One problem encountered with prior art apparatuses designed to remove structural concrete which has deteriorated is the difficulty of obtaining access to the nozzle assembly, for maintenance, repair and the replacement of nozzles or orifices when required due to the inconvenient location of the nozzle assembly lower most within the hood or hood assembly.
Another problem is that prior art apparatuses are not constructed to exclude water and debris from the area surrounding the hood, and from internal areas of the hood including the carriage and the drive mechanism for moving the carriage in the hood.
With prior art apparatuses, concrete, stones and other debris from the concrete break up chamber located within the hood escaped to other areas of the hood causing damage to the carriage or the carriage roller supports. There exists the possibility of high pressure water entering the interior or inner zone or region of the hood into the feed mechanism, or the carriage and into the power drive mechanism for the tubular shaft support and nozzle assembly.
Thus, certain of the component parts of the prior art apparatuses have been and are subject to a dirty environment which substantially decreases the useful life of the parts.